Stoker



Deli. 23, 1928.

O. P. LUETSCHER STOKER 4 Sheets-Sheet 1 Filed March 13. 1922 ymgzm'oia i 0. P. LUETSCHER STOKEB Filed March 15. 1922 4 Sheets-Sheet mm @[NVENTOR 4 W 545 MW 0. P. LUETSCHER STOKER Filed March 15. 1922 4 Sheets-Sheet 5 Oct. 23, 1928.

o. P. LUETSCHER STOKER 4 Sheets-Sheet 4 Filed March 15. 192.2

1 INVENTOR g; 7 0% Wm fiwzm-wa Patented a. 23, 1928.

PATENT OFFICE.

I OLIVER P.'I4UETSCHER, 0F IQITTSBURGH, PENNSYLVANIA.

STOKER.

.lpplication flled mart-11,13, 1922. Serial No 543,221.

.My invention relates to stokers and is di- 'rected particularly to stokers for industrial furnaces although not limited to that particular field.

In such machines the fuel is ignited and the fire bed formed at the upper edge of a retort, the burning fuel overflowing on both sides of the retort'and spreading itself out on side grates. In some stokers as heretofore constructed these side grates take the form of dead plates as there is no wind box surrounding the retort and all of the air to the tuyeres comes from a space below the fuel bed which might be designated as the ash pit, but no ash can enter it except a little of the siftings that may come through the tuyres.

Observation of the action of such tokers discloses the fact that when the fire1s first lighted or freshly cleaned the coal begins to burn on top of the retort immediately above the tuyeres and withthe-usual rate of feeding a high combustion rate is necessary to consume the amount of coal fed. Consequently a bed of clinker is formed which arches over the retort. This is forced upward by the incoming fuel and spreads the blast over a greater area by forcinggit to take a path underneath the cap of'clin er.- This action continues with more or less severeclinkering until sufiicient clinker has been formed to spread the blast out over an area large enough to bring the rate of combustion down to a point at which the fuel bed tempefiature is below the fusing point of the as From the foregoing it will be quite obvious that stokers of this type can not operate without severe clinkering especially if capacities are maintained which arewomparable with the rated capacities of the machines based on their actual continuous fuel burning capacity.

The inherent difliculty of such machines is that there is no efficient means for retarding the combustion at the, tuyeres to prevent the extremely high temperatures and at the same time supply suflicient air to complete the combustion;

My invention overcomes these and other objections by providing means for introducing a primary blast of moist air through the tuyeres and means for controlling the composition of this blast so that the temperature 1n the region of the retort may be accurately controlled to avoid clinker and build up a coke bed. Means are also provided for supplying a secondary blast through the side grates for the purpose of maintaining combustion in that area.

By the use of my invention a stoker is provided which may be'readily removed from the furnace without disturbing the permanent furnace setting. My stoker is so constructed that the tuyeres may be readily removed as units without disturbing any substantial part of thestoker. Further advantageousmechanical and operative features will be apparent upon reading'the following description in connection with the drawings showing one embodiment of my invention and in which:

Figure 1 is a front elevation of a furnace with my invention applied thereto;

Figure 2 is a vertical section on line of Figure 1;

Figure 3 is a section on line III-III of- Figure 2;

Figure 4 is a section on lineIV-IV of Figure 2; I

Figure 5 is a sectionof the rear end of the tuyere taken on a plane through the line VV of Figure 6;

Figure 6 is a perspective view of a portion of the tuyere;

Figure 7 is a front view, with certain parts rerioved, of a modification of my invention, an

Figure 8 is a side elevation of a part of the stoker shown in Figure 7, with certain parts broken away.

Referring to the drawings and particularly to Figure 1, a furnace 1 of any well known construction is shown having buck stays 2 and doors 3 and 4, with my stoker applied thereto.

The stoker is provided with a removable hopper 5 through which the coal is fed into the pusher 6 as best shown in Figure 2. The pusher 6 may be of any desired construction and is reciprocated by a piston 7 in a cylinder 8 by means of a piston rod 9 which is 'attached to the pusher in' any suitable mansired valve mechanism whereby steam is controlled to actuate the piston. The stoker is retort is supported at one end by the frame 11 and at the other end by a-casting 17 fastened in the wall 18 of the furnace and provided .with a flange 19 upon which the inner end of the retort rests.

The retort is provided at its sides with horizontal portions 20 and 21. An upstanding flange 22 is provided on each of the portions 20 and 21. Tuyeres 23 and 24 are mounted on the portions 20 and 21, respectively, of the retort as shown in Figure 4.

The tuyeres comprise holders 25 which ma be made of cast steel. The holders are hol low box-shaped members provided with grooves 26 and 27 and flan es 28 and 29 as shown in Figures 4 and 6. uyre blocks or segments 30 are provided with tongues 31 and 32 which fit into the grooves 26 and 27, respectively. These blocks are also provided withprojections 33 and 34 which bear a ainst the edges of the holders 25 as shown in F igure 6. Each of the blocks 30 is provided with recesses 35 in one side thereof so that when the blocks are assembled as shown in Figure 6 openings are produced which communicate with the interior of the holders 25. The end I block 36 is provided with a portion 37 which extends across an opening 38 in the end 39 of the holder 25. The part 37 is provided with an opening which registers with the opening 38 and a bolt 40 is passed through these registering openings and acts to hold thesection 36 in place on the holder. The

- other blocks 30 extend the length of the tuyere, the last one being placed a ainst the block 36 as shown in Fi re 5 so t at all of the blocks are held a ainst rearward longitudinal movement on t e holder for a purpose which will appear later.

Side grates 41 are placed in the combustion chamber of the furnace and are supported therein independently of the retort or tuyeres. F J

Pipes 42 and 43 connect with the tuyeres as shown in Figures 1 and 2. These pipes communicate w1th an Argand blower 44 as best shown in Figure 2. The pipes 42 and 43 are provided with sliding dampers 45 and 46 respectively, for the purpose of regulating the blast to the tuyeres. These dampers are arranged to slide in recesses formed in the flanges at the junctions of the sections in the pipes, while the stems connected to the valves extend to the exterior of the pipes, as shown in- Figs. 1 and 2. The construction of the Argand blower is well understood and it has been deemed unnecessary to illustrate the same in" detail in the drawings Obviously any other well known means may be employed in place of the Argand blower and my 7 invention is not limited to any particular 1 form of blower. As is well understood the Argand blower is so constructed that the pro-' portions of air and steam passing therethrough may' be changed by an adjustable air shutter with which said blower is equipped.

The wall 18-is provided with an opening 47 into which a ipe 48 is fitted and through which a blast 0 air is introduced to the ash pit 49.

The main frame 11 is supported by filler blocks 50. Filler blocks 51 are also provided under a pedestal 52 for the purpose of rendering the stoker easily removable from the furnace as will appear later. As will be noted by reference to Figure 2 the frame 11 of the stoker when in position snugly fits into the 'door frame 53 in the furnace wall 54. A space is provided between these members in which a packin material 55 is placed to prevent the esca e 0 air.

e modification shown in Figures 7 and 8' will now be described. The parts corres onding to similar parts in the modification s own in the other figures have been given the same numerals with the letter a afiixed thereto.

The main frame 11 carries the stoker construction and fits into a door frame 53 in the 'wall 54 of a furnace. Instead of the Argand blower shown in Figure 2, I have substituted 1 a wind. box 60. This box is 'providedwith an operating rod 61 extendingl across the same and journaled in the sides t ereof. The ends 62 of the rod are squared for the purpose of rotating the rod by means of a handle which may be a plied thereto. A bifurcated lever 63 is attached to the rod 61 and throu h .a link 64 actuates a damper 65 which sli es on the bottom of the wind box. The frame 11 is provided with an opening'66 which opens into the ash pit so that when the damper 65 is open the blast which is forced into the wind box will pass through the opening 66 into the ash pit. Pipes 42 and 43" connect with the sides of the wind box and lead upwardly to the tuyeres as in the construction shownin Figures 1 and 2. Water spray nozzles 67v are mounted in the elbows of the pipes 42 'and 43 for the purpose ,of moistening the air as it goes into the tuyres. The nozzles 67 may be of any well known construction and have I therefore notbeen shown in detail. These nozzles are mounted in sleeves 68 which are screwed into the pipes 42 and 43". I Water pipes 69 are screwed into the sleeves 68 and are connected with any suitable source of water supply. The air whichenters the wind box 60 may be preheated to any desired degree by any suitable means and'is forced into the wind box by any desired form of blower. 13

The operation of my device is as follows: The stoker is moved into'the position shown in Figure 2 and the hopper-is filled with coal and the pusher 6 reciprocated by the piston 7. This fills the retort with coal which is ignited. The primary blast through the Argan blower 44 is introduced and the blower is suitably adjusted to meet the conditions in hand and a mixture of steam and air is supplied to the tuyres through the pipes 42 and 43, the same being individually regulated by the dampers 45 and 46. This blast maintains the primary combustion of the coal which is coked. The steam in the blast prevents an excessive temperature at this point on account of its endothermic reaction with the in candescent fuel. Further feeding of coal by 6 should be stopped for any reason.

, pair having the pusher 6 causes the partially consumed coked fuel to overflow from the retort on to the side grates. After the coal has passed out upon the side grates 41 the s'econdar blast is admitted to the ash pit 49 through t e conduit 48 and the combustion regulated as conditions may require. It is understood'that the piston 7 is automatically reciprocated by steam which is controlled by a valve mechanism not shown.

The air which is supplied to the ash pit may be preheated to any desired degree and by any suitable -means. Water is circulated through the chamber 16 in, the retort for the purpose of keeping the retort cool so that it will not be injured by the high temperatures produced, especially when preheated air is used. .The cooling of theretort prevents overheating of the. same which overheating would cause the coal to coke and jam in the retort, especially if the motion of the pusher n my stoker the retort is provided with gently sloping slides and is therefore relatively flat. Thistogether with the water cooling makes it possible to start the-stoker without cleaning after a tem orary shut down..

If one o the tuyere blocks 30 should become broken or other kind of repair to the tuyere should be necessarythe tu eres may be removed from thefurnace by isconnecting the upper portions of the pipes 42 and 43 and removi the tuyeres-as units. The reeen made the tuyere is again placed in the stoker or a new tuyere may be substituted for the old.

If it is desirable to remove the stoker as a unit for re airs or otherwise, this may be easilydone' y removing the filler blocks 50 and 51, thus-allowing a small clearance between the door frame and the frame 11 whereupon the stoker may be removed from the furnace as a unit withoutdisturbing any of the permanent setting of the furnace.

If necessary or desirable, the 'entire feedin mechanism of the stoker may be removed without disturbing the tuyeres, retort or furnace setting. This is accomplished by re- .ing' said opening,

moving a few bolts which hold the parts, to-- 31 and 32 in the grooves 26 and 27, in I e d holders 25. After all the blocks 30 are in blocks 36 are placed on the ends of position, the holders and fastened by bolts 40.

The operation of the modification shown in Figures 7 and 8 is'identical with that above described with the'exception of the air blasts. In the modification the blast is introduced into the wind box and the secondary blast is controlled by the gate 65 by opening that gate the desired amount. The rimary blast is introduced into the tuyeres t rough the pipes 42 and 43* and if the air is preheated it may be moistened by introducing the water spray through the nozzles 67. By this arrangement the temperature of the retort area may be accurately controlled. From the foregoing it will be apparent that the primary and secondary blasts may of each other. The secondary blast is controlled by the gate 65 and the primary blast by the dampers 45 and 46.

My invention has many advantages, among which may be mentioned that the primary blast is independent of the secondary blast; the proportions of air and steam in the primary blast may be varied; the temperature in the region of the retort may be controlled by controlling the primary blast; the secondary blast may be controlled and the combustion on the side grates accordingly controlled; by the above means the combustion chamber may be kept free from clinker; the stoker as a unit is readil removable from the furnace without distur ing the setting; the tuyeres may be individually removed as units be controlled independently without disturbing the setting or the stoker;

to or withdrawn from the furnace-as a unit and without the removal of the stoker.

2. In combination with a furnace. having an opening through a wall thereof, an underfeed stoker having a. retort projecting into the furnace, tuyeres supported by the retort, and a wall ortion sions of the retort'and tuyere's being smaller than the opening whereby they may be refor the stoker substantially fillthe cross-sectional dimenmoved bodily from the furnace, the tuyres b'eiia separately removable through the Wall portion of the stoker.

3. In combination witha furnace'having 5 an opening in a wall thereof, a tuyere comprisin an open-sided. body adapted to be passe through the opening into the intreior of the furnace, an air connection for the tuyre body at the end of the body adjacent said opening,'and tuyere blocks fitting over 1 the ogen side of the trou h-like body to form a su stantially enclose tuyere body with the blocks thereon removable throughsaid o ening.

In testimony whereof have hereunto set my hand.

()LIVER P. LUETSCHER.

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